The broad objective of this project is an understanding of the basic metabolism of gastropod vectors of animal parasites as it relates to their biology and the biology of the intermediate stages of the parasites they harbor. The specific objectives include an elucidation of the mechanism of amino acid catabolism. Biochemical methodology is being used to elucidate the nature, cellular localization and function of the following enzymes: The transaminases, glutamate dehydrogenase, enzymes of the purine nucleotide cycle, the amino acid oxidases, carbamyl phosphate synthetase(s) and glutamine synthetase.